The present invention relates to an apparatus for braking the crankshaft of an engine when stopping of the operation of the engine.
In an engine for driving a rotary device such as a mower or tiller, an output shaft of an engine is directly coupled with a rotary body (such as a cutter blade, in the case of the mower) or coupled by way of a clutch mechanism. In either case, the rotary body continues to rotate for a while due to inertia even after stopping of the operation of the engine. In a conventional brake device for stopping the rotary body at the time of shutting off of the ignition system of the engine, a band brake is provided on a periphery of a flywheel magneto in an area corresponding to approximately 90 degrees.
When stopping the engine, the band brake is applied to the periphery of the flywheel. However, since the brake device applies the brake force against a magnet such as magnetic steel provided on the periphery of the flywheel, the wear of the magnetic steel increases the gap between a core of an ignition coil and the magnetic steel. On the other hand, heat generated during the brake application decreases the magnetism of the magnetic steel, resulting in a decrease of ignition performance.
Further, prior art concerns brake apparatus for engines. For example, Japanese utility model application laid open No. 56-160331 discloses a clutch brake apparatus. However, the apparatus requires an additional space for installation of the clutch and brake mechanisms, increasing the dimension of the machine in axial direction, and making the construction complicated. In addition, the apparatus is not applicable to a machine such as a mower having a construction allowing easy entrance of dust, sand, small stones, etc.